The Spectral Differentializer is a device invented by Egon Spengler to study the layers of a ghost.
The Spectral Differentializer is a medium-sized device that was created in order to conduct examinations of ghosts and see what they are made of. Since Slimer was the only ghost that would cooperate with them, the Ghostbusters elected to use him to test the device. Slimer was seated in front of the Differentializer. After it warmed up, the device took hold of Slimer with a grabber arm and began to peer through his layers. However, due to the heat given off by the device, the popcorn Slimer just ate popped and flooded Egon's laboratory.
- On page four of Ghostbusters Issue #9, the Spectral Differentializer makes a non-canon cameo as the screen Egon is looking at.
- On page five of Ghostbusters Volume 2 Issue #6, part of the Spectral Differentializer makes a non-canon cameo on the bottom shelf.